She bought some pictures when she was ____________ holiday __________ December, and now she is going to hang them ________ the wall.

She bought some pictures when she was ____________ holiday __________ December, and now she is going to hang them ________ the wall.

Explanation

We use preposition on before a day i.e. Holiday.

We use preposition In before a month i.e. December.

We use preposition on before for he wall.